1. Field of the Invention
The invention relates in general to a projection display apparatus, and more particularly to a digital zooming method applied to a projection display apparatus.
2. Description of the Related Art
Due to requirements of consumers for a multi-function electronic technology, a projection display apparatus tends to be designed to have a plurality of functions. For example, the projection display apparatus equipped with digital zooming function can perform an image scaling operation on a special area of the image according to a zooming multiple selected by a user.
Referring to FIG. 1, a block diagram of a conventional projection display apparatus is shown. A projection display apparatus 10 includes a zooming circuit 110, a flash memory 120, a control unit 130, a display unit 150 and an image scaler 140. The projection display apparatus 10 uses the zooming circuit 110 to perform a digital zooming function, and records a parameter table 122 in the flash memory 120. If the user wants to scale a certain region of the first image P1, the control unit 130 performs a calculation process on the first image P1 to generate a second image P2 via the zooming circuit 110 and the parameter table 122 according to a zooming multiple selected by the user. The projection display apparatus 10 scales the second image P2 by using the image scaler 140 to generate a third image P3, the third image P3 has a specific pixel count relative to the display unit 150.
However, to use the zooming circuit 110 not only reduces an available space in the conventional projection display apparatus 10, but also increases a producing cost and a market competitiveness of the conventional projection display apparatus 10. Besides, the parameter table 122 also occupies space of the flash memory 120, thereby reducing an accessible volume of the flash memory 120.